Population synthesis of isolated Neutron Stars with magneto--rotational evolution

We revisit the population synthesis of isolated radio-pulsars incorporating recent advances on the evolution of the magnetic field and the angle between the magnetic and rotational axes from new simulations of the magneto-thermal evolution and magnetosphere models, respectively. An interesting novelty in our approach is that we do not assume the existence of a death line. We discuss regions in parameter space that are more consistent with the observational data. In particular, we find that any broad distribution of birth spin periods with $P_0\lesssim 0.5$ s can fit the data, and that if the alignment angle is allowed to vary consistently with the torque model, realistic magnetospheric models are favoured compared to models with classical magneto-dipolar radiation losses. Assuming that the initial magnetic field is given by a lognormal distribution, our optimal model has mean strength $\langle\log B_0{\rm [G]}\rangle \approx 13.0-13.2$ with width $\sigma (\log B_0) = 0.6-0.7$. However, there are strong correlations between parameters. This degeneracy in the parameter space can be broken by an independent estimate of the pulsar birth rate or by future studies correlating this information with the population in other observational bands (X-rays and $\gamma$-rays).Comment: 10 pages, 9 figures, submitted and accepted to MNRAS, comments welcom

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

The use of shape-controlled metal nanoparticles has produced not only a clear enhancement in the electrocatalytic activity of different reactions of interest but also a better understanding of the effect of the surface structure on nanoscaled materials. However, it is well-accepted that a correct understanding of the correlations between shape/surface structure and electrochemical reactivity indispensably requires the use of clean surfaces. In this regard, and considering that most of the synthetic methodologies available in the literature for the preparation of these shaped metal nanoparticles employ capping agents, the development of effective surface cleaning methodologies able to remove such capping agents from the surface of the corresponding nanoparticles, becomes an extremely important prerequisite to subsequently evaluate their electrocatalytic properties for any reaction of interest. Consequently, in this contribution, we summarize the most relevant advances about surface cleaning procedures applied to different shaped metal nanoparticles for electrocatalytic purposes. It is worth mentioning that this work will only include contributions in which the surface cleanness of the samples is specifically evaluated using well-established electrochemical tools.This work has been financially supported by the MINECO of Spain through project CTQ2013-48280-C3-3-R. JSG acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante

In vitro gastrointestinal digestion of pomegranate peel (Punica granatum) flour obtained from co-products: changes in the antioxidant potential and bioactive compounds stability

The effect of in vitro gastrointestinal digestion (GID) on the recovery, bioaccessibility and stability of polyphenolic compounds, the changes in antioxidant activity and the short chain fatty acids (SCFAs) production of pomegranate peel flour (PPF) were evaluated. The extracts obtained in each step of GID were used to determine the stability of polyphenolic profile using HPLC whilst the antioxidant properties were determined using five methodologies. The SCFAs production from PPF fermentation was also determined. At the end of GID process, the bioaccessibility of phenolic and flavonoid compounds was 35.90 and 64.02%, respectively. The polyphenolic compounds decreased after GID except that for ellagic acid which increased. GID increased the chelating activity and reducing power. However, the scavenging properties were reduced. Fermentation of PPF by colonic bacteria generated acetic, propionic and butyric acids. PPF could be used in the food industry as a potential ingredient to develop functional foods that promote health benefits.info:eu-repo/semantics/publishedVersio

Bragg Coherent Diffraction Imaging for In Situ Studies in Electrocatalysis

Electrocatalysis is at the heart of a broad range of physicochemical applications that play an important role in the present and future of a sustainable economy. Among the myriad of different electrocatalysts used in this field, nanomaterials are of ubiquitous importance. An increased surface area/volume ratio compared to bulk makes nanoscale catalysts the preferred choice to perform electrocatalytic reactions. Bragg coherent diffraction imaging (BCDI) was introduced in 2006 and since has been applied to obtain 3D images of crystalline nanomaterials. BCDI provides information about the displacement field, which is directly related to strain. Lattice strain in the catalysts impacts their electronic configuration and, consequently, their binding energy with reaction intermediates. Even though there have been significant improvements since its birth, the fact that the experiments can only be performed at synchrotron facilities and its relatively low resolution to date (∼10 nm spatial resolution) have prevented the popularization of this technique. Herein, we will briefly describe the fundamentals of the technique, including the electrocatalysis relevant information that we can extract from it. Subsequently, we review some of the computational experiments that complement the BCDI data for enhanced information extraction and improved understanding of the underlying nanoscale electrocatalytic processes. We next highlight success stories of BCDI applied to different electrochemical systems and in heterogeneous catalysis to show how the technique can contribute to future studies in electrocatalysis. Finally, we outline current challenges in spatiotemporal resolution limits of BCDI and provide our perspectives on recent developments in synchrotron facilities as well as the role of machine learning and artificial intelligence in addressing them.Financial support from Brazilian agencies: P.S.F. thanks FAPESP (Grants 2017/11986-5, 2018/20952-0, and 2019/13888-6 (RAV fellowship)), CNPq (Grant136436/2019-6 (RAV fellowship)), Shell, and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences Data, Artificial Intelligence and Machine Learning at DOE Scientific User Facilities program under Award No. 34532

Synthesis and Electrocatalytic Properties of H2SO4-Induced (100) Pt Nanoparticles Prepared in Water-in-Oil Microemulsion

The increasing number of applications for shape-controlled metal nanoparticles (NPs) has led to the need for easy, cheap, and scalable methodologies. We report the synthesis of (100) preferentially oriented Pt NPs, with a particle size of 9 nm, by using a water-in-oil microemulsion method. The specific surface structure of the NPs is induced by the presence of H2SO4 in the water phase of the microemulsion. Interestingly, the results reported herein show how increasing amounts of H2SO4 lead to the formation of Pt NPs containing a larger amount of (100) sites on their surface. This preferential surface orientation is confirmed electrochemically by using the so-called hydrogen adsorption/desorption process. In addition, transmission electron microscopy measurements confirm the presence of cubic-like Pt NPs. Finally, the electrocatalytic properties of the Pt NPs are evaluated towards ammonia and CO electro-oxidations, which are (100) structure-sensitive reactions.This work has been financially supported by the MCINN-FEDER (Spain) (project CTQ 2010-16271), Generalitat Valenciana (project PROMETEO/2009/045) and in part by NASA-URC Grant No. NNX10AQ17A and NSF-NSEC Center for Hierarchical Manufactur-ing Grant No. CHM-CMMI-0531171. R. M-R is grateful to the Becas Iberoamérica, Santander Universidades-España 2012 and PR-LSAMP Bridge to Doctorate Fellowship programs

Epigenética en técnicas de reproducción asistida: razones y evidencias para una reflexión

Los procesos epigenéticos producen cambios covalentes en la cadena de ADN sin alteración en la secuencia de bases nitrogenadas. Una de las modificaciones epigenéticas más relevantes es el proceso de metilación de citosina. Este proceso es de vital importancia para mantener el silenciamiento génico en el desarrollo normal, la impronta genómica y la inactivación del cromosoma X. Así, por ejemplo, cuando se producen alteraciones en la impronta, estos pueden desencadenar enfermedades, especialmente aquellas relacionadas con defectos en el desarrollo embrionario y el proceso neoplásico. En los últimos años se ha visto que mediante el uso de técnicas de reproducción asistida (TRAs), se pueden ver aumentados los desórdenes de este tipo, motivación suficiente por la que creemos que resulta de interés un mayor conocimiento de las modificaciones epigenéticas y su relación con numerosas enfermedades y disfunciones tras el uso de TRAs, con notables consecuencias sobre el manejo, tratamiento y prevención en el futuro de enfermedades en recién nacidos. En este trabajo, se describen los mecanismos de las modificaciones epigenéticas, más concretamente la metilación de citosina, las implicaciones que tiene dicha metilación de ADN sobre disfunciones y desarrollo de enfermedades en recién nacidos, los factores implicados en TRAs causantes y/o transmisión de la metilación de ADN y, finalmente, las metodologías analíticas para la determinación del grado de metilación en ADN.Epigenetic events lead to covalent modifications at the DNA chain without mutagenic alterations in the DNA sequence. One of the most relevant epigenetic modifications corresponds to the methylation process of cytosine. The above process is of outstanding importance to keep the gene silencing of normal development, genomic imprinting and inactivation of chromosome X. Thus, for instance, when the genomic imprinting suffers alterations, it can trigger the appearance of diseases, mainly those related to defects during the embrionary development or in neoplasic processes. Over the last few years, it has been observed that via the use of assisted reproductive techniques (ARTs) a number of the above disorders and dysfunctions can be proliferated, reason enough for which we strongly demand a more profound knowledge about the epigenetic modifications and their relationships with a wide number of diseases and dysfunctions after ARTs, with notable consequences in the management, treatment and prevention of diseases in newborn babies In this work, the authors describe the mechanisms involved in epigenetic modifications -more particularly cytosine methylation-, the implications of cytosine methylation at DNA upon dysfunctions and development of diseases in newborn babies, causal factors implicated in ARTs and/or transmission of DNA methylation and, finally, the analytical methodologies used for the determination of methylation grade in DNA

Bi-modified Pt Electrodes toward Glycerol Electrooxidation in Alkaline Solution: Effects on Activity and Selectivity

Herein we investigate the effect of irreversibly adsorbed bismuth on polycrystalline platinum (Ptp) on the electrooxidation of glycerol in alkaline media by combining electrochemical, spectroscopic (in situ FTIR), and analytical (HPLC on line) techniques. We found that the activity of Ptp increases by about 5-fold when the optimal quantity of Bi ions is added to the solution. Besides, the adatom strongly impacts the reaction products by suppressing the pathways with C–C bond breaking, hindering the formation of CO (and other unknown intermediates) and enhancing the production of glycerate. Different from the results in acid media for Ptp-Bi systems where Bi blocks the oxidation pathway through the primary carbon, glycerate is the main product in alkaline media, and dihydroxyacetone is either produced in extremely low quantities or not produced. Besides, comparing our results with those in acid media, the peak current recorded at 1 mV·s–1 in this work was 1 order of magnitude higher. These results show the strong impact of the pH in the reaction rate and selectivity.Financial support from the Brazilian agencies: PSF and JLB thanks FAPESP (grants: 2016/01365-0) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. MBCS thanks PRP-FAEPEX and RAV and VYY thanks SAE-Unicamp for their scholarships. J.S-G. acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante (UATALENTO16-02)

Electrocatalytic studies on imidazolium based ionic liquids: defining experimental conditions

The number of publications devoted to studying electrochemical reactions in room temperature ionic liquids (RTILs) is constantly growing, but very few of them have been devoted to defining proper experimental conditions to obtain reproducible electrochemical results. In this work, we demonstrate that the combination of a proper RTIL purification treatment and a filtered Ar gas stream allow us to obtain featureless voltammograms in [C4mim][BF4], [C4mim][NTf2], and [C4m2im][NTf2], which otherwise present signals associated with different types of impurities such as water and some minor electroactive impurities acquired during the RTIL synthesis process. Moreover, we demonstrate that bubbling Ar, or another inert gas, through the electrolyte in order to purge O2 dissolved in RTILs is one of the major sources of water and O2 impurities incorporated in RTILs within the electrochemical cell. To overcome this source of water uptake, we have incorporated a gas stream purification filter before the gas reaches the RTIL in the electrochemical cell. To illustrate the effect of these impurities in relevant electrocatalytic studies, we study the electrocatalytic reduction of CO2 on Pt nanoparticles and the key role of an appropiate filter when the CO2 gas stream is bubbled within imidazolium based RTILs. Our cyclic voltammetric studies point out that CO2 electroreduction on Pt nanoparticles only presents activity in [C4mim][NTf2] and [C4m2im][NTf2], thus suggesting that the C-2 position on the imidazolium ring is not the key position in CO2 electrochemical reduction. In contrast, the same Pt nanoparticles are inactive towards CO2 electroreduction in [C4mim][BF4], which is a more hydrophilic RTIL.The authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) (projects CTQ2013-48280-C3-3-R and CTQ2016-76231-C2-2-R) (AEI/FEDER, UE) and from the CNRS (projet Défi Instrumentation aux limites 2015). J. S.-G. acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante (UATALENTO16-02). C. M. S.-S. acknowledges financial support from the University of Alicante, visiting researcher grant INV16-15

Realización de un congreso online para fomentar la participación y aprendizaje en reuniones científicas

Los congresos científicos son una herramienta tan valiosa como infrautilizada en el aprendizaje para estudiantes de tercer ciclo y es que, desgraciadamente, éstos no son aprovechados al máximo puesto que las intervenciones en las que los estudiantes plantean dudas o preguntas son prácticamente nulas. Con el objetivo de fomentar la participación de los estudiantes en los congresos científicos, se ha organizado y realizado un congreso online para estudiantes de máster y doctorado en el programa interuniversitario "Electroquímica. Ciencia y Tecnología", empleando la herramienta Moodle. En este congreso, los alumnos han presentado comunicaciones científicas en formato póster y se han llevado a cabo discusiones científicas sobre estas contribuciones. Para fomentar la participación de los alumnos, se han otorgado certificados de participación y premios al estudiante más participativo y al mejor póster. El congreso ha sido evaluado por parte de los participantes mediante una encuesta, con el fin de obtener un feedback para una posible próxima edición del congreso

Celebración del I Congreso Online de Jóvenes Investigadores, herramienta científica de presente y futuro

Históricamente, los congresos científicos son, y han sido, uno de los mecanismos más efectivos para la difusión y el debate del conocimiento. A pesar de ello, un ambiente altamente formal no es el más idóneo para que los estudiantes de tercer ciclo saquen el máximo rendimiento, relegándolos a un segundo plano y anulando prácticamente su participación. Con el reto de propiciar la intervención de los estudiantes de máster y doctorado, fundamentalmente a través de planteamiento de preguntas, se ha organizado y celebrado el I Congreso Online de Jóvenes Investigadores en Electroquímica. Enmarcado en los programas interuniversitarios de máster y doctorado de “Electroquímica. Ciencia y Tecnología”, y mediante la herramienta Moodle, los estudiantes han participado en el congreso mediante comunicaciones en formato de póster. Además, han podido mantener discusiones científicas y expresar sus dudas e inquietudes hacia el trabajo de sus compañeros. Para implicar al alumno, se han otorgado certificados de participación y varios premios, uno de ellos otorgado por los propios estudiantes mediante un sistema de votación. En previsión de próximas ediciones del congreso se hizo una encuesta de satisfacción y sugerencias entre los participantes